differential

1. General: Difference between comparable classes, entities, or items (such as costs and revenues) that change in quality, quantity, and degree at different rates between alternative courses of action.

2. Securities trading: Extra charge (typically 0.5 of a point or ¢12½ per share) added to the purchase price or subtracted from the selling price by a broker or dealer for odd lot (less than a round lot or standard trading unit) stock transactions. Also called odd lot differential.